Practical Network-Based Techniques for Mobile Positioning in UMTS
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Practical Network-Based Techniques for Mobile Positioning in UMTS ¨ Jakub Borkowski and Jukka Lempiainen Institute of Communications Engineering, Tampere University of Technology, P.O. Box 553, 33101 Tampere, Finland Received 1 June 2005; Revised 9 May 2006; Accepted 18 May 2006 This paper presents results of research on network-based positioning for UMTS (universal mobile telecommunication system). Two new applicable network-based cellular location methods are proposed and assessed by field measurements and simulations. The obtained results indicate that estimation of the position at a sufficient accuracy for most of the location-based services does not have to involve significant changes in the terminals and in the network infrastructure. In particular, regular UMTS terminals can be used in the presented PCM (pilot correlation method), while the other proposed method - the ECID+RTT (cell identification + round trip time) requires only minor software updates in the network and user equipment. The performed field measurements of the PCM reveal that in an urban network, 67% of users can be located with an accuracy of 70 m. In turn, simulations of the ECID+RTT report accuracy of 60 m–100 m for 67% of the location estimates in an urban scenario. Copyright © 2006 J. Borkowski and J. Lempi¨ainen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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INTRODUCTION
An ultimate aim of the mobile positioning research is to find a method providing high estimation accuracy to the user with minimum delay and at minimum cost. Development of location techniques towards defined performance objectives is pushed by the perspective of high revenues through enabling attractive location-sensitive applications together with stated safety requirements. Currently, the best positioning accuracy is provided by the AGPS (assisted global positioning system) method [1]. However, this technique has the highest hardware constraints, as UMTS (universal mobile telecommunications system) mobiles in the current market are not typically AGPS-enabled. Moreover, most of the existing UMTS networks are not ready for AGPS positioning technology, since upgrade of present equipment and implementation of additional units such as LMU (location measurement unit) is needed. Naturally, reducing the required investments for deploying technology that enables positioning with sufficient accuracy is essential in providing LBS (location-based services). Therefore, from this perspective, a motivation for cellular location techniques that are ready for immediate deployment is magnified. Positioning techniques that do not require major changes in network and in terminal and utilize only existing
network infrastructure to provide a location of the user could be directly implemented in the current networks to provide a wide range of LBS. In the long-term deployment, the cellular positioning methods could be used
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